FIGS. 14, 15 and 16 show conventional sprinkler heads.
The sprinkler head shown in FIG. 14 comprises a heart-shape body arm 20, a deflector 21, a valve plug 22, a fluid passage 20a and a glass bulb 23. In use when the glass bulb 23 is shattered by heat the valve plug 22 drops down, and water is ejected from the fluid passage 20a of the body arm 20 to hit the deflector 21 so that water sprinkles in to the desired area.
The sprinkler head shown in FIG. 15 comprises a shaped frame 24, a deflector 25, a valve plug 26, a thermal release element 27, a housing 28, an escutcheon 29 and a cover plate 30. As the temperature around the sprinkler head increases the escutcheon 29 and cover plate 30 drop down to expose the body arm 24 and deflector 25. When the thermal release element 27 has melted, the thermal release element 27 and valve plug 26 drop down, water is ejected and deflected by the deflector 25 into the desired area.
The sprinkler head in FIG. 16 comprises a body 31, a valve plug 32, a deflector guide 33, a deflector 34, a fusible pellet (not shown) and an escutcheon 35. If the pellet is melted by heat, the valve plug 32, deflector guide 33 and deflector 34 drop down a limited distance and water is ejected from the fluid passage 31a of the body 31 to hit the deflector 34 which deflects water into the desired area.
If the sprinkler head shown in FIG. 14 is connected to the distribution pipe (not shown) prior to constructing the ceiling, the heart-shaped body arm 20 obstructs fitting of the ceiling board. Conversely if the sprinkler head is fitted after the ceiling is completed it is difficult to check for any leakages. If the ceiling is to be constructed before the sprinkler head is fitted, large gaps are made in the ceiling to accommodate them when subsequently fitted; however, this is not satisfactory from an aesthetic point of view.
The sprinkler head shown in FIG. 15 could be fitted to a distribution pipe prior to constructing a ceiling; however, it is poorly designed, firstly because of the space 36a in the ceiling 36 which is required to put the body arm 24 into the housing 28 and then the housing 28 is covered by the cover plate 30. In addition, there is a problem with water distribution from the deflector 25 because there is insufficient space between the deflector 25 and the ceiling 36b.
The sprinkler head shown in FIG. 16 may also be fitted to a distribution pipe prior to constructing the ceiling. However, there are difficulties in controlling the fusible pellet and the head is expensive. It also has poor design by showing the deflector 35 and the fins 37 exposed.